We now have 24 characters with a mix of letter and numbers. Could be Base64 but we would need to determine which letters are lowercase and uppercase. Clearly numbers came from set #1. Playing a bit with the string we can determine that set #2 are lowercase and set #3 uppercase

We now have 24 characters with a mix of letter and numbers. Could be Base64 but we would need to determine which letters are lowercase and uppercase. Clearly numbers came from set #1. Playing a bit with the string we can determine that set #2 are lowercase and set #3 uppercase